This invention relates to control circuits for switching transistors and, more particularly, to a new and improved control circuit for a transistor which performs a switching action.
Conventional circuits for switching transistors include an emitter-collector snubber circuit which has a distributed inductance. When the transistor is switched off the energy stored in the distributed inductance produces a sharp voltage spike applied to the transistor. Efforts heretofore made to reduce this voltage spike have not been successful, especially in circuits using several transistors in parallel to provide increased current capacity. In addition, the noise generated in such circuits requires complicated measures to avoid interfering signals.
Accordingly, an object of the present invention is to provide a circuit for interrupting the operation of a switching transistor which is capable of reducing the rising rate (di/dt) of current flowing into a snubber circuit when a transistor used to perform switching action is switched off.
Another object of the invention is to provide such a circuit which is arranged to avoid structural restrictions and to provide higher reliability and also decrease the noise generated at the time of switching the transistor off.